The causes of COPD include the following: first, the most important factor is smoking, smoking includes their own smoking, and at the same time there is second-hand smoke. Usually, we often encounter women with emphysema, not necessarily their own smoking, but their husbands smoke and often inhale secondhand smoke may also develop COPD. Secondly, about 1/6 of patients who do not smoke also have COPD, which may be caused by the following factors, including occupational dust, occupational pollution dust, and biofuels. Thirdly, air pollution, including dust and haze, can cause COPD. Fourth, repeated infections are also one of the causes. Other factors include autoimmune disorders, airway hyperresponsiveness or age, and climatic and environmental factors, which are also causes of COPD.